“Ducking” is a term used in audio track mixing in which a background track (e.g., a music track), is attenuated when another track, such as a voice track, is active. Ducking allows the voice track to dominate the background music and thereby remain intelligible over the music. In another typical ducking implementation, audio content featuring a foreign language (e.g., in a news program) may be ducked while the audio of a translation is played simultaneously over the top of it. In these situations, the ducking is performed manually, typically as a post-processing step.
Some applications of audio ducking also exist that may be implemented in realtime. For example, an emergency broadcast system may duck all audio content that is being played back over a given system, such as broadcast television or radio, in order for the emergency broadcast to be more clearly heard. As another example, the audio playback system(s) in a vehicle, such as an airplane, may be configured to automatically duck the playback of audio content in certain situations. For instance, when the pilot activates an intercom switch to communicate with the passengers on the airplane, all audio being played back via the airplane's audio systems may be ducked so that the captain's message may be heard.
In some computing devices, especially portable devices such as smartphones and tablets, audio ducking is initiated when notifications or other communications are delivered by the device. For instance, a smartphone that is playing back audio content via an audio source may duck the audio content playback when a phone call is incoming. This may allow the user to perceive the phone call without missing it.
Some audio playback sources also provide for an automatic increase in the volume of audio content, based on a determination of ambient noise. For example, many cars have audio playback systems that will automatically increase their volume level in response to increased noise from the car's engine.
Modern headphones, earbuds, and other portable devices with audio playback functions are commonly worn or used over extended periods and in a variety of environments and situations. In some cases, a user may benefit from the private audio experience, listening to music and other audio content independently of ambient noise, including other people. Some headphones provide noise-cancelling functionality, where outward-facing microphones and associated processing detect and analyze the incoming ambient noise, and then generate sound waves that interfere with the ambient noise.
However, the desire for a private and isolated audio experience can quickly shift to a desire to regain ambient awareness, for example, when a user is listening to music but then wants to speak to a person around her. In these situations, the audio playback actually degrades the user's ability to clearly hear the person she wants to converse with. The user must either manipulate the volume or play/pause buttons to attenuate or stop the music, remove the device from their head (for a wearable device), or both. In some noise-cancelling headphones, the user may select a manual switch that modifies the noise-cancelling feature to provide a noise pass-through effect. After the conversation is finished, the user must put the device on her head again, and/or manually start the music or raise the volume again. In short, the transition from private audio experience to real-world interaction can be repetitive and cumbersome.